Imperfect Images
No telescope can form a perfect image. Even if a reflecting telescope could have a perfect mirror, or a refracting telescope could have a perfect lens, the effects of aperture diffraction are unavoidable. In reality, perfect mirrors and perfect lenses do not exist, so image aberrations in addition to aperture diffraction must be taken into account. Image aberrations can be broken down into two main classes, monochromatic, and polychromatic. In 1857, Philipp Ludwig von Seidel (1821–1896) decomposed the first order monochromatic aberrations into five constituent aberrations. They are now commonly referred to as the five Seidel Aberrations.
Read more about this topic: Optical Telescope
Famous quotes containing the words imperfect and/or images:
“Art is a reality, not a definition; inasmuch as it approaches a reality, it approaches perfection, and inasmuch as it approaches a mere definition, it is imperfect and untrue.”
—Benjamin Haydon (1786–1846)
“What images are these
That turn dull-eyed away,
Or shift Time’s filthy load,
Straighten aged knees,
Hesitate or stay?
What heads shake or nod?”
—William Butler Yeats (1865–1939)